The project's long-term objectives are to help elucidate the molecular processes involved in carcinogenesis and mutagenesis.
Specific aims relate to how the DNA lesions are handled in various eukaryotic cells. From studies with ultraviolet (UV) radiation, ionizing radiation, and other mutagens/carcinogens it is clear that DNA is the critical target for physical and chemical carcinogens and mutagens. The mere existence of lesions in DNA may not, however, be sufficient to produce mutagenesis, carcinogenesis or cell killing, since generally some type of processing is required for such lesions to be """"""""fixed"""""""" and thus result in mutagenesis, carcinogenesis or cell killing. This project examines this processing by examining DNA replication after insult of eukaryotic cells with UV (254 or 320 nm) light as well as some other mutagens/carcinogens. DNA replication was chosen since existing data indicate that it plays a crucial role in the processing of DNA lesions. There are three general areas to be explored. First, our previous work has shown that exposure of mammalian cells to UV light results in the activation of alternative sites of replicon initiation. Such an activation would allow cells to replicate DNA that would normally be prevented from being replicated by the presence of blocking lesions. This would increase cell survival, but might also increase the incidence of mutagenesis or carcinogenesis since this process does not remove lesions, but does stimulate cells to replicate regions of DNA with non-instructive bases. By using DNA fiber autoradiography we plan to continue our work in this area and to expand our study to other cells lines. Second, using DNA fiber autoradiography, we plan to continue our examination of the effects of UV light and the rate and extent of DNA fork progression. From such studies we hope to be able to identify the lesion(s) most responsible for blocking DNA fork progression. Finally, exposure to UV appears to inhibit the activation of some replicon clusters. This process appears to occur for a longer time (after exposure to UV) than does blockage to DNA fork progression. Using alkaline step elution, we plan to examine this process in detail. Examination of these three areas should increase our understanding of how cells handle potentially mutagenic/carcinogenic lesions. This, in turn, should increase our understanding of the molecular processes involved in mutagenesis and carcinogenesis.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
2R01CA032579-06
Application #
3170466
Study Section
Radiation Study Section (RAD)
Project Start
1982-03-01
Project End
1992-03-31
Budget Start
1987-04-01
Budget End
1988-03-31
Support Year
6
Fiscal Year
1987
Total Cost
Indirect Cost
Name
Northern Illinois University
Department
Type
Schools of Arts and Sciences
DUNS #
City
De Kalb
State
IL
Country
United States
Zip Code
60115
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Styer, S C; Griffiths, T D (1992) Effect of UVC light on growth, incorporation of thymidine, and DNA chain elongation in cells derived from the Indian meal moth and the cabbage looper. Radiat Res 130:72-8
Taft, S A; Ling, S Y; Griffiths, T D (1991) Effect of UV light on sister-chromatid exchanges, activation of alternative sites of replicon initiation and thymidine incorporation in CHO AA8, UV61 and UV5 cells. Mutat Res 255:257-64
Griffiths, T D; Ling, S Y (1991) Effect of UV light on DNA chain growth and replicon initiation in xeroderma pigmentosum variant cells. Mutagenesis 6:247-51
Griffiths, T D; Taft, S A; Ling, S Y (1990) Effect of UV light on DNA replication and chain elongation in Chinese hamster UV61 cells. Mutat Res 236:51-8
Griffiths, T D; Ling, S Y (1989) Effects of UV light on DNA chain growth and replicon initiation in human cells. Mutat Res 218:87-94
Styer, S C; Meechan, P J; Griffiths, T D (1989) Effects of ultraviolet light on thymidine incorporation and DNA chain elongation in photoreactivable insect cells. Photochem Photobiol 50:557-62
Griffiths, T D; Ling, S Y (1987) Activation of alternative sites of replicon initiation in Chinese hamster cells exposed to ultraviolet light. Mutat Res 184:39-46
Meechan, P J; Carpenter, J G; Griffiths, T D (1986) Recovery of subchromosomal DNA synthesis in synchronous V-79 Chinese hamster cells after ultraviolet light exposure. Photochem Photobiol 43:149-56
Griffiths, T D; Ling, S Y (1985) Effect of ultraviolet light on thymidine incorporation, DNA chain elongation and replicon initiation in wild-type and excision-deficient Chinese hamster ovary cells. Biochim Biophys Acta 826:121-8